Inflammation plays a critical role in defending a host from infectious invaders and repairing tissues following injury. However, when inflammation does not resolve appropriately it can have significant detrimental effects within the body. It is well-accepted that chronic inflammation contributes to the pathogenesis of countless diseases. This type of inflammation commonly leads to tissue destruction and/or organ failure and can lead to symptoms that can have a drastic impact on the quality of life of those afflicted.
When tissue injury occurs through physical, chemical or biological means, phospholipids in the cell membranes are first metabolized to arachidonic acid, which is further metabolized to prostaglandins through the well-known cyclooxygenase enzymes (COX-1 & COX-2). The resulting prostaglandins primarily produce the well-recognized outward effects seen at the site of injury, including edema (swelling), erythema (redness), localized fever, and pain. Simultaneously, pro-inflammatory cytokines, particularly Interleukin 1 beta (IL-1β) and Tumor Necrosis Factor alpha (TNF-α), are released by local cells and also by immune cells when they arrive at the site of injury. These pro-inflammatory cytokines amplify both the inflammatory process and the pain cascade through feedback mechanisms as demonstrated in FIG.4.
Treatments for chronic inflammatory conditions can target any of a number of enzymes or receptors within this cascade. For example, corticosteroids suppress phospholipase A2 activity, slowing the release of arachidonic acid from the conversion of phospholipids within the cell membrane, and aspirin (acetylsalicylic acid), one of the most widely known Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), non-selectively and irreversibly inhibits cyclooxygenase-1 (COX-1), one of the primary enzymes in the production of downstream prostaglandins. Few, if any, treatments however have specifically targeted the role that NF-κB plays in this inflammatory cascade.
NF-κB is a protein complex family found in the cytoplasm of nearly all animal cell types and the DNA binding activities of this transcription factor family were first reported in 1986. Once activated and translocated to the nucleus, NF-κB controls the transcription of multiple genes involved in rapidly responding to negative or harmful external cellular stimuli as demonstrated in FIG. 5.
Active NF-κB is a heterodimeric protein which consists of either a p50 monomer with a RelA monomer (p50/RelA) or a p52 monomer with a RelB monomer (p52/RelB). The Rel proteins (RelA & RelB) are a highly conserved (from species to species) DNA-binding domain known as the Rel Homology Domain (RHD) which also contain transcription activation domains (TADs) that enable them to activate target gene expression. The monomers p50 & p52 are known as NF-κB proteins and consist mainly of ankyrin repeats with two N-terminal serine residues. They also contain the RHD domain, however they lack the TADs found in the Rel proteins and therefore cannot activate gene expression in either their monomeric form or in a homodimeric (p50/p50 or p52/p52) form. They must be coupled with a Rel protein to activate the DNA sequences known collectively as κB sites.
Prior to activation, the p50/RelA heterodimer exists in the cytoplasm as an inactive complex in which it is bound to an inhibitor of κB known as IκBα, and the p52/RelB heterodimer exists as an inactive p100/RelB heterodimer in the cytoplasm. There are two well-accepted paths to activation of NF-κB, the canonical or classical pathway and the non-canonical or alternative pathway. In the canonical pathway, IκBα is serially phosphorylated by an inhibitor of κB kinase (IKK-α), targeting IκBα for ubiquitination and eventual destruction in the proteasome. In the non-canonical pathway, p100 which functions as an inhibitor of κB (IκB), is serially phosphorylated by an inhibitor of κB kinase (IKK-β) and is partially degraded to the active p52 protein. These IκB kinases (IKK-α & IKK-β) exist in a trimeric form in the cytoplasm in what is known as the IKK complex. The IKKs are coupled with the regulatory scaffold protein NF-κB Essential Modulator (NEMO) to prevent continuous activation of NF-κB. In either pathway (canonical or non-canonical), the IKK complex is activated when signaling molecules bind to cell surface receptors. Bacterial or viral antigens, various cytokines (e.g. IL-1β, TNF-α, etc.), oxidative stress, ultraviolet irradiation, and free radicals are just some of the stimuli known to trigger activation of one or the other of the NF-κB pathways, either through directly binding to these cell surface receptors or by causing other signaling molecules to be formed which then bind to the receptors.
NF-κB was initially investigated for its critical role in regulating the immune response to infection. However, in the decades since its discovery, the dysregulation of NF-κB has been associated with numerous classical inflammatory diseases such as sepsis, asthma, rheumatoid arthritis (RA), and inflammatory bowel disease (IBD). Interestingly, a number of diseases that are not obviously inflammatory in nature have also been associated with NF-κB dysregulation, including atherosclerosis, Alzheimer's disease, multiple sclerosis, diabetes, and various cancers.
In general, the NF-κB dysregulation involved in disease pathology is that of over-activation, inappropriate activation, or chronic activation. In a classic inflammatory disease like asthma, airway irritants that are only mildly irritating to a normal airway cause severe inflammation in an asthmatic airway (i.e. over-activation). In inflammatory bowel diseases such as Crohn's or gluten intolerance, components of a person's diet that are not irritating to a normal gut, cause acute inflammation which can lead to severe intestinal damage (i.e. inappropriate activation). Or, in the case of rheumatoid arthritis, the body of an RA sufferer becomes sensitized to fragments of degraded cartilage (i.e. glycosaminoglycans, type II collagen, etc.) leading to an autoimmune reaction to one's own cartilage ultimately leading to further and severe cartilage degradation (i.e. chronic activation). Logically, to treat these diseases one would seek to de-activate or inhibit NF-κB in some manner to restore its proper regulation.
Applicants have surprisingly discovered that activation of NF-κB in the gut of a host has a positive effect on many diseases and conditions, as well as treating NF-κB dysregulation. Without being bound by theory, Applicants believe that activation of NF-κB in the gut of a host results in a decrease or deactivation of NF-κB systemically in the host.